1. Field of the Invention
The invention relates to a porous media for filtering and purifying fluids, containing a combination of transition nano-metal oxide and aluminosilicate. The combination of these materials removes organic compounds from the fluid, destroys bacteria, algae and virii, and purifies the fluid in the presence or absence of UV or visible light.
2. Description of Related Art
Fluids such as air and water are frequently contaminated by organic compounds and microorganisms, and such contaminated fluids occur widely throughout the world. Such contamination is not limited to undeveloped countries, but can occur and be particularly problematic in drinking water supplies and recirculated air of buildings, airplanes, etc., in developed countries as well. Thousands of water treatment and sewage treatment facilities in the U.S. cannot afford to improve their primary treatment facilities, much less afford to construct secondary treatment facilities. Methods and materials for removing organic contaminants from water that are fast, easy to use, and easily retrofitted to existing systems would be a great benefit for all of these applications.
In addition to large scale fluid purification, there is a significant consumer market in developed countries for air and water filtration and purification devices and materials. Residential and commercial sales of water and air purification devices and media are substantial; consumers use them to attempt to remove organics and microorganisms which municipal water purification processes leave behind, and to remove VOC, pathogens and allergens from the air. Microorganisms, such as bacteria and virii, are very difficult to remove from fluids using the relatively small filters available for home or small scale commercial use.
Different techniques have been used over time to attempt to eliminate these impurities. For example, activated carbon or charcoal has been used for many years to remove volatile organic compounds (VOC) from water and air. However, the process of removal is by adsorption of the organic material onto active sites on or in pores of the carbon, resulting in eventual saturation of the carbon with adsorbed species. Eventually, the carbon will have to be replaced with fresh material, which can be time consuming and expensive. In addition, the total capacity and volumetric flow rate of fluid that activated carbon can purify can be quite limited. Flow rate, in particular, can be limited by the necessity to keep the fluid and the carbon in contact for a sufficient residence time for the adsorption to occur.
Synthetic aluminosilicates useful in water-purification have been disclosed. For example, in U.S. Pat. No. 5,612,522, the entire contents of which are incorporated herein by reference, a method is disclosed for producing a synthetic aluminosilicate that has pore sizes ranging from about 60 Å to about 250 Å by forming a sodium aluminosilicate gel in the presence of ultraviolet radiation. This material is disclosed in the patent as effective in removing dissolved oxygen from water, as well as effective in removing other contaminants, such as dissolved gases. The patent does not specifically disclose removal of organic contaminants or microorganisms from the water.
Metal oxides, and in particular, fumed metal oxides, have been found to be effective water purification materials when included or immobilized in a binder matrix, as disclosed in U.S. Ser. No. 10/445,410, filed May 27, 2003, and in U.S. Ser. No. 09/854,010, filed May 11, 2001, the entire contents of each of which are incorporated herein by reference. Unbound fumed metal oxides have been found to be useful in reducing mineral scale formation and microorganisms levels in water, as disclosed in U.S. Ser. No. 10/304,898, filed Nov. 26, 2002, the entire contents of which are incorporated herein by reference.
The use of titanium dioxide and “zeolites” as “photocatalysts” for the decomposition of phenol is disclosed in “Aqueous Solar Photocatalysis,” http://www.saskschools.ca/˜pvsd/vsfprojects/solarwaterpure/solarwaterpure/members .home.net/rod.3/main.html. The author states that phenol is adsorbed by the zeolite, and can then be decomposed by UV radiation, in effect regenerating the zeolite. The author is silent with respect to what zeolite is used, except to state that the pores of the zeolite do not exceed 0.5 to 0.6 μm, and that the zeolite has a surface area of 315 m2/g. The author states that the photocatalyst used in his experiments contained this zeolite with about 10% of its surface covered with titanium dioxide. The author speculates that it is the excitation of the titanium dioxide by UV light that causes decomposition of material adsorbed on the zeolite surface.
However, despite these materials and methods for water purification, there remains a need in the art for materials effective in removing organic contaminants and microorganisms from consumable fluids, such as water and air.